Draughty single-glazed windows let heat escape, let noise in and leave condensation running down the glass every winter morning. Double glazing tackles all three. In the UK, a typical uPVC double-glazed window costs around £400 to £1,000 fitted, and replacing every window in a three-bedroom house usually comes to £4,000 to £9,000, depending on frame material and window style.
So, is double glazing worth it? Energy savings alone rarely pay back the full cost quickly, but combined with warmer rooms, less noise, better security and a higher property value, most homeowners with single glazing or failing old units find the upgrade worthwhile.
This guide breaks down double glazing prices by frame type, realistic energy savings, the ratings to look for and cheaper alternatives such as replacing only the sealed glass units.
you have single glazing, rotten frames, failed seals, or noise and condensation problems.
your existing double glazing is sound – replacing glass units or adding draught-proofing may be enough.
Double glazing prices by frame material
| Frame | Per window (fitted) | Lifespan | Best for |
|---|---|---|---|
| uPVC | £400–£1,000 | 20–35 years | Best value, low maintenance |
| Aluminium | £700–£1,600 | 30–45 years | Slim, modern frames |
| Timber | £900–£2,000 | 40–60 years (maintained) | Period homes, conservation areas |
| Composite | £900–£1,800 | 35–50 years | Timber look without upkeep |
Bay windows, sash styles and large sizes cost more. Triple glazing typically adds 10–25% to the price.
How much could you save?
Energy Saving Trust estimates suggest replacing single glazing with A-rated double glazing can save a typical semi-detached home around £100 to £200 a year on heating, with bigger savings for detached houses. Savings from replacing old double glazing with new are much smaller.
Look for the BFRC energy rating (A++ to E) or a low U-value – the lower the U-value, the less heat escapes. Building regulations in England set minimum performance standards for replacement windows, which a registered installer must meet.
Other benefits beyond energy savings
Two panes with a sealed gap reduce traffic and street noise, especially with acoustic glass.
A warmer inner pane means fewer streaming windows and less mould on frames.
Modern multi-point locks and toughened or laminated glass are harder to break.
No cold draughts near windows, so rooms feel warmer at the same thermostat setting.
Double or triple glazing?
Triple glazing adds a third pane and usually improves thermal performance further, but the extra benefit over a high-quality A-rated double-glazed unit is modest in most UK homes. It also makes windows heavier and typically adds 10–25% to the cost. Triple glazing makes most sense in very exposed locations, new builds aiming for high efficiency or homes next to busy roads where noise reduction matters. For most people, well-installed A-rated double glazing offers the best balance of cost and performance.
Understanding the glass
Modern double-glazed units use low-emissivity (low-E) coatings that reflect heat back into the room, and the gap between panes is often filled with argon gas, which insulates better than air. Warm edge spacer bars reduce heat loss around the edge of the glass and help prevent condensation at the bottom of the pane. When comparing quotes, ask about each of these features, as two windows that look identical can perform very differently.
Cheaper alternatives
Misty glass means a failed seal. A new glass unit costs about £80–£250, keeping the frame.
An inner pane fitted behind existing windows – ideal for listed buildings and noise reduction.
New seals and strips can fix cold spots on otherwise sound windows for very little.
How to get the best price
Window prices vary widely between companies, so collect at least three written quotes for the same specification. Be cautious of high-pressure sales visits offering large “today only” discounts – a genuine price does not expire in an hour. Local independent installers are often cheaper than national brands, and replacing all windows at once is usually better value than doing them one at a time. Make sure any deposit is protected by an insurance-backed scheme.
Do you need permission for new windows?
In most houses, replacing windows like for like does not need planning permission. Different rules can apply to listed buildings, homes in conservation areas with special restrictions, and flats, where the lease or freeholder may control the style and colour of windows. If you live in one of these properties, check with your local council or freeholder before ordering, as getting it wrong can mean replacing the new windows at your own cost.
Paperwork you should receive
Replacement windows in England and Wales must meet building regulations. Installers registered with a competent person scheme such as FENSA or Certass can self-certify the work and register it, and you should receive a certificate. Keep it – solicitors will ask for it when you sell. Ask also for an insurance-backed guarantee covering deposits and workmanship.
Looking after double glazing
uPVC and composite frames need very little care: wipe them down with warm soapy water, clean drainage slots at the bottom of the frame and lubricate hinges and locks once a year. Check seals for gaps and replace worn gaskets before they let in draughts. Timber frames need repainting or re-staining every few years to keep them weatherproof.
Savings based on Energy Saving Trust estimates; prices reflect typical UK installer quotes.
Independent guide – not linked to any window company.